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It's not as simple as that IMHO. Your body uses calories from different sources differently. It's not just about energy in, energy out, that's too simplistic. In order to burn fat your body needs to not have ready access to blood glucose for energy. As an extreme example, if you ate 600 cals of sugar a day as opposed to 600 cals of protein, your body would have ready access to fuel and so would not need to burn it's fat stores. Eating the protein would mean that the body would need to convert the protein into glucose (using energy to do this) and would need to look to it's fat stores for energy.

Whilst low carbing I ate a very high calorie diet yet still managed to lose two stone in two months.

Full Member

It's not as simple as that IMHO. Your body uses calories from different sources differently. It's not just about energy in, energy out, that's too simplistic. In order to burn fat your body needs to not have ready access to blood glucose for energy. As an extreme example, if you ate 600 cals of sugar a day as opposed to 600 cals of protein, your body would have ready access to fuel and so would not need to burn it's fat stores. Eating the protein would mean that the body would need to convert the protein into glucose (using energy to do this) and would need to look to it's fat stores for energy.

Whilst low carbing I ate a very high calorie diet yet still managed to lose two stone in two months.

Biochemistry is an immensely complicated science, but the Laws of Thermodynamics still apply. You cannot create energy so if you're only consuming 600kcal per day and your maintenance is 2000kcal per day the defect has to be made up by your body's energy store, regardless of whether the 600kcal is coming from carbs or protein.

Gold Member

But you would burn more energy if you ate high protein foods because you need energy to convert them to glucose in addition to other body processes. Whereas eating simple sugars would mean you wouldn't need to break them down as much therefore using less energy?

Full Member

But you would burn more energy if you ate high protein foods because you need energy to convert them to glucose in addition to other body processes. Whereas eating simple sugars would mean you wouldn't need to break them down as much therefore using less energy?

This is called the thermic effect of food (TEF). Protein does indeed have a higher TEF than fat or carbs. Very simply, up to 30% of protein calories ingested are used to process the protein whereas up to 10% of fat and carb calories are used for processing.

However the effects of this on weight loss are insignificant. For example, 1000kcal of protein vs 1000kcal of carbs would result in a difference of just 233kcal TEF - there would be a difference of a pound after about 15 weeks. There are other reasons too, too complicated to get into here, but here's one: Proteins are not all the same - some are much longer than others requiring more energy to breakdown. Conversely some are much shorter, requiring less energy to breakdown. The 30% TEF is an average. And thermodynamics still applies - weight change is still down to energy taken in vs energy used.

Full Member

Biochemistry is an immensely complicated science, but the Laws of Thermodynamics still apply. You cannot create energy so if you're only consuming 600kcal per day and your maintenance is 2000kcal per day the defect has to be made up by your body's energy store, regardless of whether the 600kcal is coming from carbs or protein.

I'd hazard a guess that I'm a little more familiar with the research and biochemistry in general than you (the clue is in my username).

Thermodynamic Laws are the only laws relating to energy. In the post above yours I discussed briefly TEF and why this is insignificant when it comes to overall weight loss, and why it does not violate thermodynamics. Biochemistry is not somehow magically exempt from the physical laws that govern the universe.

Ketosis is not required for fat loss. Your body is quite capable of burning both glycogen and fat simultaneously and does so every day. Ketosis can have the advantage of blunting the appetite but is not required.

Mass and energy are equivalent. (E=mc^2)

600kcal of carbs is the same as 600kcal of protein in grams. As I stated in my previous post, losses would be pretty much identical. In fact, I came across a study a couple of years back where the participants had better losses when eating higher carbs!

We're not talking about health. We're talking about weight loss. And there are so many variables with health and diet that it would take a while to get into - which I have little inclination to do as this is a support forum, and certainly not a serious scientific discussion.

LOL I'd hazard a guess that you are quite a bit more patronizing than me too. Hey, do you think if I change my user name to Elvis I could get a gig in Vegas? LOL Really, do you think that giving yourself that name will make other people defer to your opinion on all matters biochemical? Please.

I have no interest in debating this topic to be honest, I did at one time but you can read it all over the net, it never get's resolved. At calorie levels as low as 600 then it probably makes little difference but all I know is I can eat a vast amount of calories on a low carb diet and drop stones. If I practically starve myself on a high carb low fat diet I really struggle to shift anything. Same as eating lots of saturated fat is supposed to give my high blood pressure, increased cholesterol, poor diabetic control, blah, blah, blah when the opposite of that is true.

Read the studies by all means, but there aren't too many out there that you can rip apart the methodology. I followed lot's of the established 'truths' for years, didn't do me any good.

Silver Member

This is called the thermic effect of food (TEF). Protein does indeed have a higher TEF than fat or carbs. Very simply, up to 30% of protein calories ingested are used to process the protein whereas up to 10% of fat and carb calories are used for processing.

However the effects of this on weight loss are insignificant. For example, 1000kcal of protein vs 1000kcal of carbs would result in a difference of just 233kcal TEF - there would be a difference of a pound after about 15 weeks. There are other reasons too, too complicated to get into here, but here's one: Proteins are not all the same - some are much longer than others requiring more energy to breakdown. Conversely some are much shorter, requiring less energy to breakdown. The 30% TEF is an average. And thermodynamics still applies - weight change is still down to energy taken in vs energy used.

Therefore 15 weeks making a difference of 233 cal a day every day would be more like 24,465 = 7lb? I think if this is right then it's great that i can lose 7lb of extra weight in 15 weeks by eating an extra 233 cal a day (assuming pure protein).

Silver Member

Come on you lot, doesn't matter how we lose weight as long as we are healthy and it is the right method for yourself personally. Everyones body reacts differently to different things. I say call it quits! Lol

Full Member

No, just pointing out that my information doesn't come from internet debate and misquoted studies that you find all over diet forums online. I chose that username because it reflects something about me... same reason most people choose specific usernames.

I've actually seen many many things in my short time on this forum that count as some seriously dubious interpretations of the science. This is really the first time I've pointed it out. The rest of the time I refrain (and as a pedantic person I can tell you that's not easy! lol).

Everyone and their mother thinks they understand advanced biochemistry when the truth is it is an unbelievably complex science. Nutrition is one of the most difficult areas. It's funny and yet worrying at the same time.

I have no interest in debating this topic to be honest, I did at one time but you can read it all over the net, it never get's resolved. At calorie levels as low as 600 then it probably makes little difference but all I know is I can eat a vast amount of calories on a low carb diet and drop stones. If I practically starve myself on a high carb low fat diet I really struggle to shift anything. Same as eating lots of saturated fat is supposed to give my high blood pressure, increased cholesterol, poor diabetic control, blah, blah, blah when the opposite of that is true.

It's well established that individuals are notoriously bad at estimating energy intake. I'd guess if you were put on a metabolic ward diet and tested against different macronutrient intakes at identical energy levels, weight loss would be nearly identical (accounting for differences in water weight). Happens every time. You are not immune to thermodynamics.

However, if you genuinely believe you are exempt from thermodynamics, CERN, NASA, and many energy companies would love to speak to you...

That said, I agree that the information about saturated fat has been highly skewed. Thank the likes of Ancel Keys for that one.

LOL I don't just read them. The problem is that studies are highly specific. It's very difficult to just take the results and apply them directly to get the same results.

And no study has absolutely perfect methodology. Many have outright bad methodology. Nutritional biochemistry is notoriously difficult to study. You change one thing and everything else changes, so you don't really know what's causing the results. It's a nightmare to say the least.

I don't just follow 'established truths'. One of my current interests is recommended protein intake - I think the current recommendations of around 50g per day are too low. I also think the vast majority of humans would be better off eating 120g carbs or less. And we don't get anywhere near enough vitamins, minerals and essential fatty acids.

Therefore 15 weeks making a difference of 233 cal a day every day would be more like 24,465 = 7lb? I think if this is right then it's great that i can lose 7lb of extra weight in 15 weeks by eating an extra 233 cal a day (assuming pure protein).

I'm sorry my calculation was supposed to be for days not weeks! Yes you are absolutely right - 15 days for an extra pound. But again, as you said, that would require pure protein consumption. 1000kcal of pure protein would be damn hard! It's very satiating. Of course, if you're into your lean meats and cottage cheese... lol